Glaucoma is considered to be a group of diseases wherein the entoptic tissue (particularly function of optic nerve cell) is damaged from lesions causing an abnormal ocular tension. Normally, the principal factors of the mechanism causing lesions are considered to be ischemic symptoms and disorder of optic nerve axonal flow due to mechanical compression in the lamina cribrosa caused by an increase in ocular tension. However, the mechanism of the increase in ocular tension is not clear at present.
For the treatment of the disease, glaucoma, a drug or surgical therapy has been mainly performed aiming at returning the increased ocular tension to a normal level. There are few treatments for protecting an optical nerve function directly. For instance, a vitamin B12 formulation can be used as a nutrient agent for protecting the optical nerve, and a calcium antagonist or an enzyme formulation can be used for the purpose of improving blood flow in the optic disc to protect the optical nerve cells. However, effectiveness of these agents on the disorder of the visual field caused by glaucoma is not clear. Besides, there is a problem that side effects can occur during a long-term usage thereof.
Therefore, the purpose of the present invention is to provide a therapeutic agent enabling an effective drug therapy for glaucoma. Further purpose of the present invention is to provide a therapeutic agent for glaucoma which has reduced side effects related to a long-term usage thereof.